1. Field of the Invention
This invention relates to a cooling system of a multi-cylinder engine. More particularly, it relates to a cooling system simple in structure and capable of attaining an improved cooling effect on the tops of cylinder liners each of which receives heat transmitted from a corresponding top ring on a corresponding piston.
2. Detailed Description of the Related Art
In a multi-cylinder engine, a water jacket in a cylinder block cannot extend to a top deck of the block from the viewpoint of structural strength. However, at the very top deck, each cylinder liner on the block will receive a great amount of heat transmitted from a corresponding top ring on a corresponding piston when the latter is near and at its top dead center position. Therefore, it has been proposed in recent years that an oil groove be formed on the top deck of the cylinder block to surround the corresponding cylinder liner and that some of the engine oil from a main oil gallery (not shown) is circulated through the oil grooves, to thereby suppress any temperature rise of each of the cylinder liners due to the heat transmitted from the corresponding top ring on the corresponding piston when the latter is near and at its top dead center position.
However, in the conventional system, the oil grooves are respectively connected to the main oil gallery through oil pipes arranged outside the cylinder block so as to equalize the cooling performance of the respective oil grooves. Such an arrangement requires complex machining and installation and an increase in the number of parts because of the external piping. Moreover, there is a risk that oil may leak from joints along the piping.
In view of the above, it is an object of the present invention to provide a cooling system which is simple in structure and which can effectively cool a top of each cylinder liner and its neighboring area.
In order to attain the above-mentioned object, the invention provides a cooling system of a multicylinder engine, which comprises oil grooves each arranged in a top deck of a cylinder block to surround a corresponding cylinder liner, supply and return channels in the cylinder block and connected to an oil pump and an oil pan, respectively, communication holes each for interconnecting the adjacent oil grooves in series and inflow and outflow holes in the cylinder block for connecting the most upstream and downstream oil grooves to the supply and return channels, respectively, thereby circulating engine oil through the oil grooves during an operation of the engine to effectively cool a top of each cylinder liner and a neighboring area thereof.
A preferred embodiment of the invention will be described with reference to the drawings.